Stain-resisting alloy



01 copper.

Patented l 'eb. 7, 1933 UNITED STATES PATENT OFFICE FREDERICK M. BECKE'I, OF NEW YORK, N. Y., ASSIGNOR TO ELECTRO METALLURGICAL COMPANY, A CORPORATION OF WEST VIRGINIA s'mm-ansrsrme ALLOY No Drawing.

This invention relates to stain-resisting alloys containing, as essential constituents, the metals iron, chromium, manganese and copper.

In an application bearing Serial No. 435,- 957, filed by me on March 14, 1930, I have described alloys consisting essentially of iron, chromium and manganese; and I have shown that within the limits of composition given in the said application, the alloys combine deep-drawing properties with high resistance to stainin and corrosion, and exhibit this combination of properties not only when uenched from temperatures of about 1000 to 1150 C., but also when air-cooled from like temperatures. The alloys discussed in my said prior application contain about 16%-22% of chromium; about 5%15% of manganese; and up to about 0.3% of carbon. When the carbon is below about 0.12% the alloys are especially soft and ductile, but not quite so strong as when the carbon is higher.

I have now found that copper may be added to the alloys of my prior application iving new alloys with desirable properties. guch new alloys, when the copper content'is suitably adjusted, are strain-resistant in approximately the same degree as the alloys of my prior application; and while the copper tends slightly to increase the hardness of the alloys, an appropriate addition of copper raises the Erichsen value and gives such a combination of physical properties as to.

indicate excellent deep-drawing qualities, an inference which is confirmed by actual drawing tests.

B adding copper to the alloys of my prior app ication it is possible with a me ium manganese content, say in the vicinity of 8%, to equal or, it seems probable, distinctly to su ass the drawing qualities obtainable wit out copper by incorporating a higher proportion of manganese. The present invention therefore offers the possibilities of providing still better alloys than those described in my prior application, and of lowering the cost of the allo s by replacing a part of the manganese wit the cheaper met-.

Application filed April 16, 1930. Serial No. 444,876.

Although I have done a large amount of experimental work on the new alloys it has not been feasible to test all possible compositions, and it is deemed unsafe in this field to permit the conclusions to wander far from the experimental basis. I therefore refrain from setting precise limits on the additions of copper which may be useful. Such limits are not of the essence of the invention, and

in practice limiting values of the copper con-- tent would be avoided in View of the impossibility in even the best metallurgical practice of working to precise limits. With this qualification it may be said that the useful copper range lies between the approximate limits of 0.25% and 2.5%. When the copper content is too high, the alloy tends to become hot-short. l/Vith the manganese at 8% or less the copper may rise to 2.5% and perhaps beyond, but with higher manganese percentages, in the vicinity of 14%, 2.5% of copper seems to be excessive, or at least not to be recommended. Alloys containing 3% of. copper with as little as 6% of manganese were definitely hot-short, and broke up during forging.

As stated above, the chromium may be varied through about the range (16%22%) given in my prior application, but my experimental work has been largely confined to compositions containing about 18% of chromium, it having been established in prior work with iron-chromium, iron-chromiumnickel, and iron-chromium-manganese alloys that a chromium percentage not far from this value is in most cases quite satisfactory, and found in the present investigation that about 18% of chromium is equally satisfac-,

physical tests carried out'on the res ective alloys as quenched from 1050-1150 Bo- Elonduo- Yield Max. amnmm- 0? Mn point mung; 8:101:01!

10210. area Per ' "As in the case of the alloys of application Serial No. 435,957 the'chromium percentages which appear most promising fall between the approximate limits of 17% and 21%. Since the addition of cop er permits the manganese percentage to be owered, the preferred' range for manganese in the coppercontaining allo s is defined by the approximate limits 6 o and 10%. I claim:-

1. A stain-resisting iron-base alloy containing chromium about 16% to 22%; manganese about 5% to 15%; and carbon, the

carbon content being not more than 0.3%; copper about 0.25% to 3.0%; with the balance substantially iron.

2. A stain-resistmg iron-base alloy having deep-drawing properties and containing chromium about 16% to 22%; manganese about 5% to 15%; copper about 0.25% to 2.5%; and carbon, the carbon content being not more than 0.3%; with the balance substantially iron.

3. A stain-resisting iron-base alloy having deep-drawing properties and containing chromium about 16% to 22%; manganese about 5% to 15%; copper about 0.25% to 2.5%; and carbon, the carbon content being ,not more than 0.12%; with the balance substantially iron. 1

4. A stain-resisting iron-base alloy having deep-drawing properties and containing chromium about 16% to 22% manganese about 6% to 10%; copper about 0.25% to 2.5%; and carbon, the carbon content being not more than 0.12%; with the balance substantially iron.

5. A stain-resisting iron-base alloy having deep-drawing pro erties and containing chromium about 1 to 21%; manganese about 6% to 10%; copper about 0.25%.. to 2.5%; and carbon, the carbon content being not more than 0.12%; with the balance substantially iron.

In testimon whereof I aflix my si ature.

F EDERIK M. BEG 'r. 

